Modular heat recovery steam generator having parallel offset headers

Abstract

A modular type heat recovery steam generator (HRSG) utilizes multiple pairs of parallel offset upper headers and into which at least two rows of vertically-oriented tubes are connected also to a lower header. The upper headers in each pair are offset from each other by a distance equal to the overall width of up to four rows of tubes, and the tubes connected to each header of the pair are located on opposite sides of the headers. Also, the adjacent end of each header pair overlap each other by a distance equal 0.5-2 times the spacing between adjacent tubes. The header arrangement and tube configuration of each module provides a generator assembly which is compact and facilitates fabrication and installation of the modular generator assembly.

I claim: 
     
       1. A modular heat recovery generator utilizing at least two parallel upper and lower pressurizable headers each connected together by tubes, which generator comprises: a horizontally extending casing;   a first elongated pressurizable upper header extending horizontally and transversely within said casing;   at least two rows of vertically-oriented tubes each connected pressure-tightly to said first upper header and also connected pressure-tightly to a corresponding elongated lower header; and   a second elongated pressurizable upper header located parallel to and offset from said first upper header, said second upper header having at least two rows of vertically-oriented tubes connected pressure-tightly to the second header and also connected pressure-tightly to a corresponding lower header, wherein the tubes connected to said first upper header are located on a side opposite from the tubes connected to said second upper header, and the adjacent ends of said first and second headers overlap each other, so as to provide dual adjacent tube banks within said casing of the modular heat recovery generator assembly.   
     
     
       2. The heat recovery generator of claim 1, wherein four rows of parallel vertically-oriented spaced-apart tubes are connected to each said upper and lower headers. 
     
     
       3. The heat recovery generator of claim 1, wherein the header pair adjacent ends overlap by a distance equal to 0.5-2 times the spacing between the adjacent rows of vertical tubes. 
     
     
       4. The heat recovery generator of claim 1, wherein said first upper and lower headers together with their connecting tubes form a first heat exchange panel. 
     
     
       5. The heat recovery generator of claim 1, wherein said vertically oriented tubes are finned type tubes. 
     
     
       6. The heat recovery generator of claim 1, wherein said headers each have diameter of 4-24 inches and a length of 5-15 feet. 
     
     
       7. The heat recovery generator of claim 1, wherein said tubes are 1-3 inch diameter and 20-70 feet long. 
     
     
       8. The heat recovery generator of claim 4, wherein a plurality of said heat exchange panels are connected to a steam drum. 
     
     
       9. A modular type heat recovery generator having parallel offset upper and lower pressurizable headers connected together by vertically-oriented tubes, the generator comprising: a horizontally extending casing provided in two parallel parts;   a first elongated pressurizable upper header extending horizontally within a first part of said casing;   four rows of vertically-oriented finned type tubes each tube connected pressure-tightly to said first header and also connected to a corresponding elongated lower header to form a first heat exchanger panel; and   a second elongated pressurizable upper header located parallel to and offset from said first upper header, said second upper header having four rows of vertically-oriented finned tubes connected pressure-tightly to the second header and also connected to a corresponding lower header to form a second heat exchanger panel, wherein the tubes connected to said first upper header are located on a side opposite from the tubes connected to said second upper header the adjacent ends of said upper and lower panels overlap each other, so as to provide dual adjacent heat exchanger panels within said casing of the modular heat recovery generator assembly.   
     
     
       10. A method for installing a heat recovery generator, comprising: (a) providing a first heat exchanger module including parallel upper and lower pressurizable headers each having tubes connected to said headers all on one side of the headers;   (b) providing a second heat exchange module including upper and lower pressurizable headers and having tubes provided on the header side opposite those for said first module, and erecting said second module so that the headers are offset from the headers in said first module and having adjacent ends of the headers overlapping the adjacent end headers of said first module; and   (c) connecting together casing members for each module so as to enclose said first and second modules to provide a compact heat recovery generator.